AT&T was the top ranked full service wireless carrier, according to J.D. Power's latest survey. MetroPCS was the top-ranked carrier for customer service among wireless providers concentrated on the no-contract market. The biggest customer satisfaction improvement, however, went to T-Mobile.

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The biggest takeaway from the J.D. Power study, conducted from July to December 2013, is that there are more customer service calls and the problems are becoming more complicated. Seventeen percent of full-service wireless customers said their customer service issues were resolved in less than five minutes. Twenty percent said problems were resolved in 25 minutes.

Meanwhile, customers are having to call their carriers more than once. Twenty three percent of wireless customers are re-contacting their carriers by phone. And a fourth of those re-contact calls last more than 25 minutes.

The upshot is that carriers' inability to resolve problems in one shot is hurting customer service and costing the companies more money.

J.D. Power said that AT&T narrowly edged out Verizon Wireless. In J.D. Power's last study of wireless carrier satisfaction, T-Mobile was at the bottom behind Sprint. This time around T-Mobile wasn't far behind the two leaders. T-Mobile's 2014 score of 778 on a 1,000 point scale was an improvement on its previous 760 score. Sprint's score was 757, down from 771 before.

Photo by J.D. Power

On the no-contract front, MetroPCS, owned by T-Mobile, ranked best in customer satisfaction.